Short message services (SMSs) deliver short text messages to mobile transceivers operating in a communication network, and a service is implemented in the network according to an industry-standard SMS protocol. An SMS message typically consists of a relatively small number of alphanumeric characters, and a mobile transceiver operating in such a network may be implemented to receive and/or transmit SMS messages. SMS messages may also be transmitted to the mobile transceiver in other ways, for example, by generating the SMS message on a computer terminal coupled to the Internet. The message is then forwarded to a central SMS service center (SMSC), coupled through a network backbone to a mobile switching center of the network, via the Internet. The SMSC then transmits the SMS message to the mobile transceiver.
The communication network supports both SMS and voice communication. In attempting to set up a voice communication, a user initially makes use of common air channels and computing resources at the BTS to negotiate a required call configuration. Once the voice communication is implemented, dedicated air channels are allocated to the user for the duration of the call. In contrast to voice communication within the network, an SMS message transmission places considerably fewer demands on the network. By its very nature, channel bandwidth for an SMS message is considerably smaller than dedicated traffic channel bandwidth used by a voice communication; the amount of processing and number of resources used by the BTS are less than those used for the dedicated traffic channel; and time of transmission of the SMS message is considerably shorter than time for a typical voice communication. Typically, an SMS message may be transmitted using common and/or dedicated channels.
If the communication network operates under a code division multiple access (CDMA) protocol such as the CDMA2000 protocol, published as TIA/EIA/IS-2000.5-A-1 by the Telecommunications Industry Association, Arlington, Va., SMS messages are transmitted as data burst messages (DBM) having a pre-defined code.
Because of the less demanding nature of SMS messages, in times of high overall network demand an SMS transmission may have considerably more chance of being processed than a voice transmission, since dedicated traffic channels used for the voice transmission may become overloaded while common channels are still available. Such times may be caused by natural events such as earthquakes or floods, or by a man-made event such as a terrorist attack.
However, while SMS messages inherently place less demand on network resources than voice transmissions, SMS messages are less secure than even an unsecured voice transmission. A recipient of an unsecured voice transmission is able to judge from the sound if the voice transmission is genuine; a recipient of an SMS transmission is not able to form such a judgment. In times of high overall network demand, the possibility of an incorrect or inadvertent SMS message rises. Thus, a method for upgrading the security and veracity of SMS transmissions is required.